Teledyne 326, 327 and 328 - Oxygen analyzers - Manual (Page 9)

1-3 Teledyne Analytical Instruments
Introduction Introduction Introduction Introduction Introduction Model 326/327/328 Model 326/327/328 Model 326/327/328 Model 326/327/328 Model 326/327/328
diagram is then included with the drawings in the instruction manual to
illustrate the sample flow path.
1.3 Models 327R Description
Model 327R is a semi-explosion-proof version of the 326R series. The
specific explosion-proof design is dependent on area classification and the
specific installation. For example, the analysis section of the 327R contain-
ing the Micro-Fuel Cell, and related conditioning components, can be
housed in an explosion-proof enclosure. If the sensor is placed within the
process or in a flow-through block, such that the explosion-proof classifica-
tion is maintained, then no analysis section enclosure may be necessary.
The standard Model 327R analysis section is a bulkhead-mounted, cast
aluminum enclosure with a screw-on cover, and is separate from the control
unit, which can be either panel mounted (327RA) or bulkhead mounted
(326RB). The sensor and the electrical interconnections are accessed by
removing the cover on the explosion-proof analysis section. Interconnecting
wiring is fed through sealed fittings in the wall of the enclosure. A sample/
calibrate selector valve and a flow control/flow meter are normally attached
to the outer right-hand wall of the enclosure. The entire analysis section
conforms to the area classification specified at the time of purchase (usually
Class I, Div. I, Group D).
The control unit is designed for remote mounting in nonhazardous areas
and is basically the same control unit as is used for the Model 326R, except
that the measuring cell and related sample handling components are placed
in the analysis section. Panel mount (327RA) and bulkhead mount (327RB)
styles are available for the control unit.
1.4 Models 327RAC/327RBC Description
The 327RAC and 327RBC models have separate control, analysis, and
probe units. The analysis units can be controlled remotely.
In models approved by CENELEC (Comité Européen de Normalisation
Electronique), safety-barrier boxes isolate the probes from the control units,
making them intrinsically safe. In addition, the probes are approved by
BASEEFA (British Approvals Service for Electrical Equipment in Flam-
mable Atmospheres).
The control unit of the 327RAC/RBC has an integral meter, power on-
off switch and range switch, protective fuses, sample path selection capabil-
ity, calibration (span) control, and the various plug-in printed circuit boards